JPH02245455A - High bypass ratio turbofan engine - Google Patents

Abstract

PURPOSE: To enhance the output power by coupling double reversion type turbine blades to a fan part and a booster compressor through an shaft device in a lower pressure turbine device, and by dividing the transmitted force to the fan part and the booster compressor by means of a reduction gear device. CONSTITUTION: A turbofan engine incorporates a fan part 12, a booster compressor 14, a core part 18 having a high pressure compressor and a low pressure double reversion type turbine device for driving the fan part 12 and the booster compressor 14, which are arranged successively in the mentioned order. The double inversion turbine includes a set of rotary turbine blades 22 extended from an inner drum 24, and a set of reversible rotary turbine blades 26 extending from an outer drum 28, and in this arrangement, an inner shaft 36 and an outer shaft 38 connect between the inner drum 24 and the fan part 12 and between the outer drum 28 and the booster compressor 14, respectively. Further, the engine incorporates a reduction gear device 34 for dividing the power which can be used for the turbine blades, into a power for the booster compressor 14 and a power for the fan part 12.

Description

DETAILED DESCRIPTION OF THE INVENTION BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to turbofan engines, particularly high bypass ratio turbofan engines having a low pressure, partially geared counter-rotating turbine driving a booster compressor and fan section. Regarding the fan engine.

[Description of related technology] High bypass ratio turbofan engine, approximately 8:1
Turbofan engines having bypass ratios above tend to be heavy and expensive. This is because low-speed, low-pressure fan-driven turbines, also referred to as power turbines, and low-speed booster compressors each require a large number of stages to achieve the required aerodynamic work indicated by the thermodynamic power cycle. This is for the purpose of Also, low speed booster compressors create significant icing problems at relatively low rotational speeds.

In FIG. 1, a prior art high bypass ratio turbofan engine 100 has a low pressure or power turbine 102 with a booster compressor 104 located forward of a core section 106 and a booster compressor 104 located forward of the booster compressor 104. The provided fan section 108 is driven via a drive shaft 110. Typically, a reduction gear 112 is connected to the booster compressor 104 to reduce the rotational speed of the output turbine of the turbine section 102 to the desired rotational speed of the fan section 108.
and fan portion 108 on shaft 110 . In this way, the booster compressor 104 is rotated at the same high rotational speed as the turbine 102 and the fan section 1
08 is rotated via reduction gear 112 at the low shaft speed necessary to increase fan efficiency.

However, the engine arrangement shown in FIG. 1 has two significant drawbacks. First, reduction gear 112 must transfer all fan drive power from shaft 110 to fan section 108 . Therefore, reduction gear 112 is necessarily very heavy and requires a large and inefficient lubricating oil cooler due to the inherent low efficiency and thermal losses of reduction gears.

Second, because the maximum available rotational speed is limited by the stress limits of the turbine blades, the number of stages in the LP tube must be relatively large to maintain efficient stage loading. A large number of LP turbine stages increases weight and rotor dynamic design issues.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to operate the fan, booster, and power turbine without (a) exceeding stress-induced turbine speed limits and (b) transmitting all of the power turbine power through the transmission box. To provide a high bypass ratio turbofan engine that utilizes gears to match and optimize the rotational speed of the engine.

Yet another object of the present invention is to match and optimize the rotational speeds of fans, boosters, and counter-rotating power turbines so that counter-rotating power turbine blades and associated drums operate at different rotational speeds (RPMs) and directions. The purpose of the present invention is to provide a high bypass ratio turbofan engine.

Yet another object of the invention is to - compact, lightweight and -
To provide a high bypass ratio turbofan engine, a rumble reduction gear is utilized on the shaft between the fan and the booster compressor.

Still another object of the present invention is that the drive turbine for the booster compressor and fan section is made smaller and lighter with fewer turbine stages, but still powered to operate the booster compressor and fan section at optimum performance levels. An object of the present invention is to provide a high bypass ratio turbofan engine that meets the requirements.

Other objects and advantages of the invention are set forth below, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instruments and combinations specified in the claims.

To achieve the above objects, a high bypass ratio turbofan engine in accordance with the objects of the invention embodied and generally described herein is provided with a fan section and downstream of the fan section with respect to combustion gas flow through the engine. The booster compressor that has been removed will be used overnight.

The core portion is provided behind the booster compressor, and the fan portion and the low pressure turbine device that drives the booster compressor are provided behind the core. The low pressure turbine arrangement has at least one axially spaced row of rotating blades and a set of axially spaced counter-rotating or counter-rotating turbine blades, the blades rotating at different speeds and in different directions. Outer and inner shaft devices are provided for coupling the turbine blades to the booster compressor and the counter-rotating turbine blades to the fan section, respectively. Reduction gearing is provided to couple the high speed turbine blades to the fan section and to reduce the rotational speed of the outer shaft, which matches the output of the low pressure turbine to the speed and direction of the fan section, thereby improving the use of the turbine blades. The possible power is transmitted in a split manner between the fan section and the booster compressor.

A first set of turbine blades is mounted on the inner drum and extends radially outwardly, a counter-rotating turbine blade is mounted on the outer drum and extends radially inwardly, and the row of rotating blades is connected to the row of counter-rotating turbine blades. Preferably, they intersect. Preferably, the inner drum is connected to an outer shaft arrangement, and the outer drum is connected to an inner shaft arrangement, although the mounting is reversed.

Preferably, the first set of blades rotates at a higher rotational speed or number of revolutions than the intersecting counter-rotating turbine blades. This helps optimize engine performance and minimize gearbox size and weight and engine complexity.

The outer and inner shaft devices have oppositely rotating outer and inner concentric shafts provided as dual spools;
Preferably, the inner shaft extends between the outer drum having counter-rotating turbine blades and the fan section to directly drive the fan section.

It is further preferred that the reduction gearing has a reduction gear with an input shaft connected to the outer shaft of the shaft arrangement and an output shaft connected to the fan section. The reduction gear also has a device for reversing the direction of rotation of the outer shaft in the shaft arrangement to match the rotation direction and speed of the outer shaft of the reduction gear with the rotation direction and speed of the inner shaft, thereby rotating the fan section. It is preferable to supplement the input required for

The drawings attached hereto illustrate preferred embodiments of the invention and, together with the general description above and the description of the preferred embodiments below, will serve to explain the invention in detail.

C Embodiment] Description of Preferred Embodiments Hereinafter, preferred embodiments of the present invention will be described based on the drawings.

The high bypass ratio turbofan engine 10 of the present invention shown in FIG. It has a booster compressor 14.

Furthermore, the engine 1G has a core portion 18 provided behind the booster compressor 14. Typically, the core portion 18
has a high pressure compressor communicating with a combustion chamber that exhausts hot combustion products through one or more high pressure turbines. These elements of core 18 are not shown because they are typical of the core portion of a turbofan engine, as will be readily apparent to those skilled in the art.

According to the invention, the engine 10 further includes a low pressure turbine arrangement located behind the core and driving the fan section and the booster compressor. As shown, the low pressure turbine system has a counter-rotating turbine, generally designated 20. Counter-rotating turbine 20 has at least one set of rotating turbine blades 22 extending from an inner drum 24 mounted on bearings within engine 10 for independent rotation. Additionally, the counter-rotating turbine 2o has at least one set of counter-rotating turbine blades 26 extending from a rotatable casing or outer drum 28 and surrounding the inner drum 24 in opposite directions. In this embodiment, the first rotating turbine blade 2
2 is a higher rotational speed R than the counter-rotating turbine blade 26
Designed and configured to operate with PM. A rotatable seal 32 seals outer drum 28 to frame 34 of engine 10.

In accordance with the present invention, engine 10 further includes an outer shaft arrangement that couples the turbine blades to the booster compressor and an inner shaft arrangement that couples the counter-rotating turbine directly to the fan section. As shown, the inner and outer shaft devices have counter-rotating concentric inner and outer shafts 36.38 mounted as double spools in respective bearings 30.31. The inner shaft 36 is connected directly to the counter-rotating turbine blades 26 and outer drum 28 at one end and to the fan section 12 at the other end, driving the fan section 12 at the same rotational speed as the counter-rotating turbine blades and outer drum 28. Drive directly.

Outer shaft 38 directly couples first turbine blade 22 and inner drum 24 to booster compressor 14 via connecting shaft 4o, and connects booster compressor 14 to first turbine blade 2
It is driven at the same high rotational speed as 2.

According to the invention, the engine 1o further couples the turbine blades to the fan section, reduces its rotational speed to match the rotational speed of the fan section, and divides the usable power of the turbine blades between the booster compressor and the fan. It has a reduction gear device. As shown, the reduction gearing has a reduction gear 42, the reduction gear 42 being the first turbine blade 2.
2 and an input shaft 44 directly driven by the outer shaft of the shaft device coupled to the inner drum 24, and an outer output shaft 46 coupled to the fan section 12 for driving the fan. The reduction gear 42 has a high rotational speed of the first turbine blade 22 and an inner shaft 3 equal to the rotational speed of the fan section 12.
It acts to match the low rotational speed of 6.

Additionally, the reduction gear 42 includes a device for reversing the direction of rotation of the outer shaft so that the direction of rotation of the output shaft 46 matches the direction of rotation of the inner shaft to complement and supplement the shaft power transmitted to the fan portion 12. have The operating condition of the reduction gear 42 with the device for reversing the direction of rotation of the outer shaft 38 does not limit or limit the scope of the invention. Many common implementations of reduction gears 42 that can be used with the present invention are known to those skilled in the art. For example, but not in a limited sense, in 1984 Mac-Gra Hill Co.
v 11111) by Darle W. Dudley (Practical Gear Design Handbook).

The present invention, as illustrated in the embodiment of FIG. 2, has several advantages over the conventional or prior art technique illustrated in FIG. First, the first turbine blades 22 rotate at a high speed to improve the efficiency of the low pressure turbine 20 and drive the booster compressor 14 at the same high rotational speed so that the booster compressor 14 has better efficiency. It is configured. Second
Additionally, fewer stages are required in the booster compressor 14 to achieve the same output, and the icing problems associated with booster compressors operated at low rotational speeds are substantially eliminated. Third, for a given turbine stress limit on the turbine blades of low pressure turbine 20, the relative velocities between the successive rows of blades and the counter-rotating blades (because the elements counter-rotate) are lower than those of the prior art. Because they can be designed larger than fan-driven turbines, more work can be extracted. Fourth, because the reduction gear 42 transmits only a portion of the fan output, the weight and size of the reduction gear 42 and the lubricant cooling system can be reduced. lastly,
In order to obtain the same shaft power as a low pressure turbine of prior art construction for the same turbine blade stress limit, the low pressure turbine 20 requires -fewer stages.

The invention shown in FIG. 2 allows power to be distributed between the speed range and the inner and outer shafts 36,38.

By way of example, but not limitation, typical power splits and operating speeds for shafts 36,38 are as follows. Here, the rotational speed of the SI-axis 36 (R, P, M,), Sz
- rotational speed (R, P, M, ) of shaft 38, T+-torque of shaft 36, T2-torque of shaft 38, and HP-power of each shaft 36, 38, designated 1 and 2, respectively.

Example; SI -2000 (Sl +
52)2/(Sz)2=49/25(Sz/S+
) 2-6. 25 7:/T+ =1. 0HP2 /HP
I - 2,5 blaster compressor HP - 20% of total HP 51HPZ Total HP - 28,6%
S+HP/Fan HP -35.7% reduction gear HP
/Total HP -51.4% reduction gear HP/Fan H
P-64.3% In the above example, the engine shaft in Figure 1! 10 rotates at a speed S2, for the same change in enthalpy before and after the counter-rotating turbine 20 and before and after the turbine 102, one membrane force or output work is directly related to the ratio of the square of the respective shaft speeds. The number of turbine stages required for the counter-rotating turbine 20 is approximately half - or 49/25, as compared to that required for the low pressure turbine 102 of the engine in prior art configurations.

Additionally, the number of stages required for the booster compressor 14 may be reduced by the construction of the engine in accordance with the present technique as compared to the prior art turbofan engine 100 shown in FIG. - A booster compressor rotating at the same speed as the first turbine blade 22 rather than at the normal fan speed RPM increases the power output per membrane force.

Finally, the size, weight, and lubricant cooler volume of the reduction gear 42 in the engine according to the present technique are significantly smaller than the prior art engine 100 shown in FIG. only about 64.3% of the required reduction gear and lubricant cooler.

In the above embodiment, the arbitrary rotational speed ratio between shaft 38 and shaft 36 is selected to be 2.5:1. The exact ratio of shaft RPM can be varied to strike a favorable compromise between the cost and weight of counter-rotating turbine 20 and booster compressor 14. For example, a 2.0:1 ratio between the rotational speeds of shafts 36 and 38 may result in a larger counter-rotating turbine 20 and booster compressor 14, but reduced weight and a smaller reduction gear 42. .

The optimum ratio of rotational speeds between shafts 36 and 38 can be selected for each application within the operating range of the particular engine.

Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details, representative apparatus and embodiments shown and described. Accordingly, one is not bound by such details without departing from the spirit and scope of the general inventive concept as defined by the claims and their equivalents.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a conventional high-bypass ratio turbofan engine in which all shaft power transmitted to the fan is transmitted through a reduction gearing, and FIG. 2 is a high-bypass-ratio turbofan incorporating the present invention. It is a schematic diagram of an engine. Explanation of main codes 1G...Turbofan engine, 12...
Fan portion, 14... Booster compressor, 18... Core portion, 20... Counter rotating turbine, 22... Turbine blade, 24... Inner drum, 26... Counter rotating turbine blade, 28 ...outer drum, 30.
31...Bearing, 32...Seal, 34...Frame, 36...Inner shaft, 38...Outer shaft, 40...
Connection shaft Mi 42... Reduction gear, 44... Input shaft, 46
...output shaft.

Claims (1)

Claims: 1. a fan section; a booster compressor disposed aft of the fan section with respect to combustion gas flow through the engine; and a core section disposed aft of the booster compressor section; at least one a counter-rotating turbine having a set of rotatable first turbine blades and at least one set of oppositely rotatable second turbine blades, the turbine arrangement being disposed aft of the core portion; an outer shaft assembly that couples the booster compressor to the booster compressor; an inner shaft assembly that couples the counter-rotating turbine blades to the fan section; and an inner shaft assembly that couples the outer shaft assembly to the fan section to reduce the rotational speed of the fan section. a high bypass ratio turbofan engine including a reduction gearing for matching the rotational speed and direction of the sections and thereby dividing the usable power of the first turbine blade between the fan section and the booster compressor. 2. The engine of claim 1, wherein the first turbine blade is operative to operate at a higher rotational speed than the counter-rotating turbine blade. 3. The inner and outer shaft devices have concentric inner and outer shafts arranged as double spools, respectively, and the inner shaft extends directly between the counter-rotating turbine plate and the fan section. The engine of claim 1 driving the fan portion. 4. The turbine blades are provided in an axially spaced row of inner blades and extend radially outwardly from a rotatable inner drum, the inner drum being fixed to the outer shaft, and the counter-rotating turbine blades extending radially inwardly from a rotatable outer drum provided in an axially spaced row of outer blades and disposed about the inner drum, the outer drum being fixedly connected to the inner shaft; , The engine according to claim 1. 5. The reduction gear device includes a reduction gear including an input shaft connected to the outer shaft and an outer shaft connected to the fan portion, and the reduction gear has a rotation direction of the outer shaft that is aligned with the inner shaft. 5. The engine of claim 4, further comprising a device for reversing the direction of rotation of said outer shaft to match the direction of rotation of said outer shaft.